Over-center gimbal actuation lock

Abstract

Embodiments are directed to a propulsion assembly for an aircraft. The propulsion assembly comprises a mast, a hub assembly coupled to the mast and having a gimballing degree of freedom relative to the mast, the hub assembly having an inner hub wall spaced part from the mast, a gimbal lock positioned about the mast, the gimbal lock configured to fit between the inner hub wall and the mast in an engaged position, and an over-center locking mechanism coupled to the gimbal lock. The gimbal lock is movable between a disengaged position and the engaged position relative to the hub assembly. The gimbal lock enables the gimballing degree of freedom in the disengaged position and disables the gimballing degree of freedom in the engaged position. The over-center locking mechanism is configured to move the gimbal lock between the engaged position and the disengaged position.

What is claimed is: 
     
       1. A propulsion assembly for an aircraft, comprising:
 a mast; 
 a hub assembly coupled to the mast and having a gimballing degree of freedom relative to the mast, the hub assembly having an inner hub wall spaced part from the mast; 
 a gimbal lock positioned about the mast, the gimbal lock configured to fit between the inner hub wall and the mast in an engaged position; and 
 an over-center locking mechanism coupled to the gimbal lock, the over-center locking mechanism having a pivot idler coupled to the mast and a spring-loaded link coupled between the pivot idler and the gimbal lock; 
 wherein the pivot idler is configured to rotate between a locked over-center position and an open position, the pivot idler configured to be held in the locked over-center position by the spring-loaded link and configured to be held in the open position by a centrifugal force generated by rotation of the mast or by a spring force; 
 wherein the gimbal lock is movable between a disengaged position and the engaged position relative to the hub assembly, the gimbal lock enabling the gimballing degree of freedom in the disengaged position and disabling the gimballing degree of freedom in the engaged position; and 
 wherein the over-center locking mechanism is configured to move the gimbal lock between the engaged position and the disengaged position. 
 
     
     
       2. The propulsion assembly of  claim 1 , further comprising:
 a mounting bracket attached to the mast, wherein the pivot idler is coupled to the mast by the mounting bracket. 
 
     
     
       3. The propulsion assembly of  claim 1 , further comprising:
 an activation idler coupled to a joint between the pivot idler and the spring-loaded link; 
 wherein movement of the activation idler in a first direction causes the hub lock to move toward the disengaged position and movement of the activation idler in a second direction causes the hub lock to move toward the engaged position. 
 
     
     
       4. The propulsion assembly of  claim 3 , further comprising:
 an actuator coupled to the activation idler, wherein the actuator is configured to move the activation idler alternatively in the first direction and in the second direction. 
 
     
     
       5. The propulsion assembly of  claim 4 , wherein the actuator is an electronic motor. 
     
     
       6. The propulsion assembly of  claim 3 , further comprising:
 one or more mechanical stops configured to prevent movement of the activation idler beyond a fixed position. 
 
     
     
       7. The propulsion assembly of  claim 1 , further comprising:
 a plurality of rollers on the gimbal lock, the rollers configured to align the gimbal lock and the hub assembly when the gimbal lock is moved to the engaged position. 
 
     
     
       8. The propulsion assembly of  claim 1 , further comprising:
 a hub extension coupled to the hub assembly, the hub extension positioned about the mast and forming at least a portion of the inner hub wall spaced part from the mast. 
 
     
     
       9. A propulsion assembly for an aircraft, comprising:
 a mast; 
 a hub assembly coupled to the mast and having a gimballing degree of freedom relative to the mast, the hub assembly having an inner hub wall spaced part from the mast; 
 a gimbal lock positioned about the mast, the gimbal lock configured to fit between the inner hub wall and the mast in an engaged position; and 
 an over-center locking mechanism coupled to the gimbal lock, the over-center locking mechanism comprising a plurality of pivot idlers coupled to the mast by a mounting assembly; 
 a plurality of spring-loaded links, each spring-loaded link coupled between an individual pivot idler and the gimbal lock; and 
 an activation idler coupled to hinged joints between each pivot idler and spring-loaded link; 
 wherein movement of the activation idler in a first direction causes each pivot idler and spring-loaded link to fold together thereby moving the hub lock toward a disengaged position relative to the hub assembly; and 
 wherein movement of the activation idler in a second direction causes each pivot idler and spring-loaded link to align thereby moving the hub lock toward an engaged position relative to the hub assembly. 
 
     
     
       10. The propulsion assembly of  claim 9 , wherein two pivot idlers are positioned on opposite sides of the mast; and
 wherein the activation idler has two arms extending across opposite sides of the mast, each arm coupled to a separate pivot idler. 
 
     
     
       11. The propulsion assembly of  claim 9 , wherein two pivot idlers are positioned on opposite sides of the mast; and
 wherein the two pivot idlers are joined by a linking member. 
 
     
     
       12. An aircraft, comprising:
 a fuselage; 
 a wing coupled to the fuselage; and 
 a propulsion assembly rotatably coupled to the wing, the propulsion assembly comprising:
 a mast; 
 a hub assembly coupled to the mast and having a gimballing degree of freedom relative to the mast, the hub assembly having an inner hub wall spaced part from the mast; 
 a gimbal lock positioned about the mast, the gimbal lock configured to fit between the inner hub wall and the mast in an engaged position; and 
 an over-center locking mechanism coupled to the gimbal lock, the over-center locking mechanism comprising:
 two pivot idlers coupled to the mast by a mounting assembly; 
 two spring-loaded links, each spring-loaded link coupled between an individual pivot idler and the gimbal lock, wherein pairs of pivot idlers and spring-loaded links are coupled by a hinged join; and 
 an activation idler coupled to the hinged joints on each pair of pivot idler and spring-loaded link; 
 
 
 wherein the gimbal lock is movable between a disengaged position and the engaged position relative to the hub assembly, the gimbal lock enabling the gimballing degree of freedom in the disengaged position and disabling the gimballing degree of freedom in the engaged position; and 
 wherein the over-center locking mechanism is configured to move the gimbal lock between the engaged position and the disengaged position. 
 
     
     
       13. The aircraft of  claim 12 , wherein the pivot idlers are positioned on opposite sides of the mast; and
 wherein the activation idler comprises two arms extending across opposite sides of the mast, each arm coupled to a separate hinged joint. 
 
     
     
       14. The aircraft of  claim 12 , further comprising:
 an actuator coupled to the activation idler and configured to move the actuation idler in a first direction and in a second direction; 
 wherein movement of the activation idler in the first direction causes the hub lock to move toward the disengaged position and movement of the activation idler in a second direction causes the hub lock to move toward the engaged position. 
 
     
     
       15. The aircraft of  claim 14 , wherein the actuator is an electronic motor. 
     
     
       16. The aircraft of  claim 12 , wherein the pivot idlers are configured to rotate between a locked over-center position and an open position;
 wherein the pivot idlers are held in the locked over-center position by the spring-loaded links; and 
 wherein the pivot idlers are held in the open position by a centrifugal force generated by rotation of the mast or by a spring force. 
 
     
     
       17. The aircraft of  claim 14 , wherein movement of the activation idler in the first direction causes each pivot idler and associated spring-loaded link to fold together thereby moving the hub lock toward the disengaged position; and
 wherein movement of the activation idler in the second direction causes each pivot idler and associated spring-loaded link to align thereby moving the hub lock toward the engaged position.